This invention relates to an initializing circuit arrangement for a counter circuit, more particularly an initializing circuit arrangement for a counter circuit in which count correction terminals are also used for initialization.
Digital counters utilized in a digital time piece, for example, for displaying seconds, minutes, hours, dates or week days generally display a random count when a power source is connected so that it is necessary to initialize the counters at such time.
Correction of the count is also necessary when the user wishes to match the displayed time with a correct time.
Conventionally, initialization and correction of the count of a counter have been made with a circuit shown in FIG. 1 which includes input terminals 1 and 1' for applying a source voltage and connected to terminals V.sub.DD and V.sub.SS of an integrated circuit 2 of a digital time piece. As the integrated circuit 2 may be used C-MOS IC type .mu.PD848C manufactured and sold by Nippon Electric Co., Tokyo Japan, and external circuits are connected to terminals labelled with terminal numbers as shown on the integrated circuit 2. The integrated circuit 2 comprises a crystal oscillation circuit connected to a crystal oscillator 3, a frequency divider for dividing the output frequency of the crystal oscillation circuit, a plurality of counters which count the number of the output signals of the frequency divider for respectively producing pulses at each one minute, ten minutes and one hour, a correction circuit for correcting the counts of these counters, a circuit for initializing the counters to make them have predetermined initial values when a pulse is applied to an initializing terminal I, and a decoder for converting the counts into decimal values supplied to display elements.
There are also provided normal open switches SW.sub.H and SW.sub.M which when closed applies high level signals to terminals H and M for correcting an hour counter which produces a pulse at an interval of one hour, and a minute counter which produces a pulse at each one minute, the hour counter and minute counter being included in the plurality of digital counters described above.
With the prior art circuit, when a source switch SW1 is closed to apply the voltage of a source E to the counters for the purpose of initially setting the counts of respective digital counters in the integrated circuit 2, a pulse produced by the initial charging current supplied to a capacitor C1 from the source E is applied to the initializing terminal I.
For this reason, the prior art circuit requires a terminal (or pin) I for use only for initialization for the counters in the integrated circuit 2. Such a terminal can not be used for other purposes thus limiting the design of the integrated circuit which must be designed such that it can be applied for wide applications with a limited number of terminals.